Dual-Ion-Mode MALDI MS Detection of Small Molecules with the O–P,N-Doped Carbon/Graphene Matrix

Abstract

It is challenging to realize a dual-ion mode of matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) for detecting small molecules. Herein, graphene coated by porous amorphous carbon with P−O surface group and codoped by phosphorus and nitrogen (O−P,N-C/G) was synthesized from an aerogel formed by phytic acid, polyaniline, and electrochemically exfoliated graphene. The carbon material synthesized has the feature of large surface area (583 m 2 /g), good electrical conductivity, strong UV absorption, heteroatom doping, and surface functional groups suitable for laser-induced desorption/ionization. It was employed as a novel matrix suitable for both positive-ion and negative-ion modes in MALDI-TOF MS for the analysis of various small molecules including amino acids, small peptides, saccharides, drugs, and environmental pollutants, significantly outperforming control materials and a traditional CHCA (α-cyano-4hydroxycinnamic acid) or 2,5-dihydroxybenzoic (DHB) matrix. Remarkably, the detection limit of the anticancer drugs (5fluorouracil and ellagic acid) reaches 50 pmol. In addition, nice MALDI-TOF MS images can be mapped to detect mixed amino acids corresponding to homogeneous distribution of ion intensity. The monosaccharides and disaccharides can be distinguished by using the new matrix. Last but not least, it can be used to quantitatively detect glucose in human serum and soft drinks (glucose/fructose, 203.1 mM) without adding standards.

Chemically heterogeneous carbon dots enhanced cholesterol detection by MALDI TOF mass spectrometry

“…A graphene matrix led to a high sensitivity and resolution in the detection of non-polar compounds, such as sterols in the MALDI MS approach [26][27][28]. Doped CDs with N, O and P have been used as substrates for the quantification of small molecules (glucose, uric acid, or amino acids) in both modes (positive and negative), and they improved an electronic density of matrices [29][30], which is an important detection parameter.…”

Aptamer‐Functionalized Fractal Nanoplasmonics‐Assisted Laser Desorption/Ionization Mass Spectrometry for Metabolite Detection

“…Compared with other nanomaterials used for MALDI MS analysis of glucose or other metabolites, [11,20,22b,24] our developed Apt‐AuNFs have many features (Table S3), including facile to prepare, high stability (storage at 4 °C for months), high reproducibility, etc. Moreover, our fabricated Apt‐AuNFs with rough nanoshells favor high ionization efficiency, and the introduction of aptamers allows Apt‐AuNFs for efficient trap of target analytes on their surface.…”

Synthesis of magnetic core–shell Fe3O4@PDA@Cu-MOFs composites for enrichment of microcystin-LR by MALDI-TOF MS analysis

“…For example, HPLC is more precise than the other methods, but they require expensive equipment, operation complexity and long analysis time. Recently, matrix-assisted laser desorption/ ionisation time-of-ight mass spectrometry (MALDI-TOF MS) has been widely applied for the detection and analysis of various compounds such as proteins, 22,23 peptides, 22,24 and small molecules 25,26 because it is a rapid, simple and sensitive technique. However, the detection limit of MALDI-TOF MS is high and this makes it unsuitable as per the WHO advisory level for drinking water.…”